Pattern forming method

ABSTRACT

A pattern-forming method includes forming a resist underlayer film on a substrate using a resist underlayer film-forming composition. The resist underlayer film-forming composition includes a base component, and a crosslinking agent. A content of hydrogen atom in the resist underlayer film is from 0 to 50 atom %. The crosslinking agent has a partial structure represented by a following general formula (i). X represents an oxygen atom, a sulfur atom, or —NR—. R represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbon atoms. n 1  is an integer from 1 to 6. R 1  represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbon atoms.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of the U.S. patentapplication Ser. No. 13/430,691 filed Mar. 27, 2012, which in turn is acontinuation application of International Application No.PCT/JP2010/066592, filed Sep. 24, 2010, which claims priority toJapanese Patent Application No. 2009-225440, filed Sep. 29, 2009. Thecontents of these applications are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pattern-forming method.

2. Discussion of the Background

An integrated circuit device has been produced using a multilayer resistprocess that implements a reduction in pattern size in order to achievea higher degree of integration. When using the multilayer resistprocess, a liquid resist underlayer film-forming composition and aliquid photoresist composition are sequentially applied to a substrate.A mask pattern is transferred to the photoresist film using a reductionprojection aligner (stepper), and the photoresist film is developedusing an appropriate developer to obtain a photoresist pattern. Thephotoresist pattern is transferred to the resist underlayer film bydry-etching. The pattern of the resist underlayer film is transferred tothe substrate by dry-etching to obtain a substrate having a desiredpattern. A multilayer resist process that utilizes one resist underlayerfilm may be referred to as “two-layer resist process”, and a multilayerresist process that utilizes two resist underlayer films may be referredto as “three-layer resist process”.

The resist underlayer film normally functions as an antireflective filmthat absorbs radiation reflected by the substrate. The resist underlayerfilm that comes in direct contact with the substrate is normally formedusing a material having a high carbon content. The etching selectivitywhen processing the substrate is improved when the material for formingthe resist underlayer film has a high carbon content, so that thepattern can be transferred more accurately. A thermosetting phenolnovolac resin is well-known as the material for forming the resistunderlayer film. It has been known that a resist underlayer film formedusing a composition that contains an acenaphthylene polymer exhibitsgood properties, for example in JP-A 2000-143937 and JP-A 2001-40293.

However, the resist underlayer film may be over-etched when furtherreducing the size of the etching pattern. Therefore, an improvement inpattern transfer capability and etching resistance has been desired. Inparticular, it has been desired to prevent a situation in which thepattern of the resist underlayer film is bent when transferring a finepattern using the resist underlayer film as a photomask.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a pattern-formingmethod includes forming a resist underlayer film on a substrate using aresist underlayer film-forming composition. An intermediate layer isformed on the resist underlayer film. A resist composition is applied tothe resist underlayer film on which the intermediate layer is formed toform a resist film. The resist film is exposed by selectively applyingradiation to the resist film. The exposed resist film is developed toform a resist pattern. The intermediate layer, the resist underlayerfilm, and the substrate are dry-etched using the resist pattern as amask to form a given pattern on the substrate. The resist underlayerfilm-forming composition includes a base component and a crosslinkingagent. A content of hydrogen atom in the resist underlayer film is from0 to 50 atom %.

The crosslinking agent has a partial structure represented by afollowing general formula (i).

X represents an oxygen atom, a sulfur atom, or —NR—, wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, and in a case where aplurality of X are present, each of the plurality of X is eitheridentical or different. n₁ is an integer from 1 to 6. R¹ represents ahydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 30 carbon atoms, wherein in a case where a pluralityof R¹ are present, each of the plurality of R¹ is either identical ordifferent.

DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present invention are as follows.

-   [1] A pattern-forming method comprising:-   (1) a resist underlayer film-forming process that includes forming a    resist underlayer film on a substrate using a resist underlayer    film-forming composition;-   (1′) an intermediate layer-forming process that includes forming an    intermediate layer on the resist underlayer film;-   (2) a resist film-forming process that includes forming a resist    film by applying a resist composition to the resist underlayer film    on which the intermediate layer is formed;-   (3) an exposure process that includes exposing the resist film by    selectively applying radiation to the resist film;-   (4) a resist pattern-forming process that includes developing the    exposed resist film to form a resist pattern; and-   (5) a pattern-forming process that includes dry-etching the    intermediate layer, the resist underlayer film, and the substrate    using the resist pattern as a mask to form a given pattern on the    substrate; characterized in

that the resist underlayer film-forming composition comprises (A) a basecomponent, and (B) a crosslinking agent having a partial structurerepresented by the following general formula (i),

wherein X represents an oxygen atom, a sulfur atom, or —NR— (wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms), provided that a pluralityof X may be either identical or different when a plurality of X arepresent, n₁ is an integer from 1 to 6, and R¹ represents a hydrogenatom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having6 to 30 carbon atoms, provided that a plurality of R¹ may be eitheridentical or different when a plurality of R¹ are present.

-   [2] The pattern-forming method according to [1] above, wherein the    crosslinking agent (B) is at least one of a compound represented by    the following general formula (b1-1) and a compound represented by    the following general formula (b2),

wherein X represents an oxygen atom, a sulfur atom, or —NR— (wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms), provided that a pluralityof X may be either identical or different when a plurality of X arepresent, n₂ is an integer from 1 to 5, n₃ is independently an integerfrom 1 to 4, m is independently 0 or 1, R¹ represents a hydrogen atom,an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to30 carbon atoms, provided that a plurality of R¹ may be either identicalor different when a plurality of R¹ are present, R² represents ahydrogen atom, a hydroxyl group, an alkyl group having 1 to 9 carbonatoms, or an aryl group having 6 to 22 carbon atoms, provided that aplurality of R² may be either identical or different when a plurality ofR² are present, and R³ represents a single bond, an oxygen atom, anester group, a carbonyl group, a chain-like hydrocarbon group having 1to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbonatoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, anitrogen atom, a sulfur atom, or an (n₂+1)-valent group formed byarbitrarily combining these groups and atoms,

wherein X represents an oxygen atom, a sulfur atom, or —NR— (wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms), provided that a pluralityof X may be either identical or different when a plurality of X arepresent, n₄ is an integer from 1 to 5, m is 0 or 1, R¹ represents ahydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 30 carbon atoms, provided that a plurality of R¹ maybe either identical or different when a plurality of R¹ are present, andR² represents a hydrogen atom, a hydroxyl group, an alkyl group having 1to 9 carbon atoms, or an aryl group having 6 to 22 carbon atoms.

-   [3] The pattern-forming method according to [1] above, wherein the    crosslinking agent (B) is a compound represented by the following    general formula (b1-2),

wherein n₅ is an integer from 1 to 5, R⁵ represents independently ahydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 30 carbon atoms, and R⁶ represents a single bond, anoxygen atom, an ester group, a carbonyl group, a chain-like hydrocarbongroup having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having3 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 30carbon atoms, a nitrogen atom, a sulfur atom, or an (n₅+1)-valent groupformed by arbitrarily combining these groups and atoms.

-   [4] The pattern-forming method according to [1] above, wherein the    crosslinking agent (B) is a compound represented by the following    general formula (b1-3),

wherein R⁸ represents independently a hydrogen atom, an alkyl grouphaving 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbonatoms, and R⁹ represents a single bond, an oxygen atom, an ester group,a carbonyl group, a chain-like hydrocarbon group having 1 to 30 carbonatoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, anaromatic hydrocarbon group having 6 to 30 carbon atoms, a sulfur atom,—NR— (wherein R represents a hydrogen atom, an alkyl group having 1 to 9carbon atoms, or an aryl group having 6 to 30 carbon atoms), or adivalent group formed by arbitrarily combining these groups and atoms.

-   [5] The pattern-forming method according to any one of [1] to [4]    above, wherein the base component (A) is a novolac resin, a resol    resin, a styrene resin, an acenaphthylene resin, or a resin having a    fullerene skeleton.-   [6] The pattern-forming method according to any one of [1] to [5]    above, wherein the resist underlayer film-forming composition    further comprises (C) a solvent.-   [7] A resist underlayer film-forming composition that is used for a    pattern-forming method including:-   (1) a resist underlayer film-forming process that includes forming a    resist underlayer film on a substrate using the resist underlayer    film-forming composition;-   (1′) an intermediate layer-forming process that includes forming an    intermediate layer on the resist underlayer film;-   (2) a resist film-forming process that includes forming a resist    film by applying a resist composition to the resist underlayer film    on which the intermediate layer is formed;-   (3) an exposure process that includes exposing the resist film by    selectively applying radiation to the resist film;-   (4) a resist pattern-forming process that includes developing the    exposed resist film to form a resist pattern; and-   (5) a pattern-forming process that includes dry-etching the    intermediate layer, the resist underlayer film, and the substrate    using the resist pattern as a mask to form a given pattern on the    substrate; characterized in that

the resist underlayer film-forming composition comprising (A) a basecomponent, and (B) a crosslinking agent that includes a partialstructure represented by the following general formula (i),

wherein X represents an oxygen atom, a sulfur atom, or —NR— (wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms), provided that a pluralityof X may be either identical or different when a plurality of X arepresent, n₁ is an integer from 1 to 6, and R¹ represents a hydrogenatom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having6 to 30 carbon atoms, provided that a plurality of R¹ may be eitheridentical or different when a plurality of R¹ are present.

According to the pattern-forming method of the embodiment of the presentinvention in which a specific resist underlayer film-forming compositionis used, a resist underlayer film can easily be formed on a substrate,which leads to excellent etching resistance, and suppresses a situationin which the underlayer film pattern is bent when transferring a finepattern by etching. Moreover, the resist pattern can be transferred tothe substrate with excellent reproducibility. Since the underlayer filmpattern is not bent when etching the substrate, an increase in yield isexpected to be achieved in microfabrication employed in a lithographicprocess, and particularly the production of integrated circuit devices.

According to the resist underlayer film-forming composition of theembodiment of the present invention, a resist underlayer film can beformed which functions as an antireflective film and exhibits anexcellent pattern transfer capability and etching resistance. Inaddition, a resist underlayer film can easily be formed on a substrate,which suppresses a situation in which the underlayer film pattern isbent when a substrate is subjected to etching. A resist underlayer filmformed using the resist underlayer film-forming composition of theembodiment of the present invention exhibits an excellent patterntransfer capability and excellent etching selectivity during a dryetching process (i.e., the resist underlayer film is rarely over-etched,and the resist pattern can be transferred to the substrate with goodreproducibility).

Hereinafter the embodiments will be described in detail.

1. Resist Underlayer Film-forming Composition

The resist underlayer film-forming composition of the embodiment of thepresent invention is used for a resist underlayer film-forming processof a pattern-forming method (described later), and includes (A) a basecomponent, and (B) a crosslinking agent having a specific structure.

(A) Base Component

In the composition of the embodiment of the present invention, anorganic compound is used as the base component for the resist underlayerfilm. The organic compound may be used singly or in combination of twoor more types thereof. The base component (hereinafter may be referredto as “base component (A)”) is an organic compound having a film-formingcapability.

Specific examples of the base component include (A1) a resin having anaromatic ring, and (A2) a compound having a fullerene skeleton.

(A1) Resin Having Aromatic Ring

Examples of the resin having an aromatic ring (hereinafter may bereferred to as “resin (A1)”) include a novolac resin, a resol resin, astyrene resin, an acenaphthylene resin, a resin having a fullereneskeleton, derivatives thereof, and the like.

Examples of the novolac resin include a resin obtained by reacting oneor more phenolic compounds with one or more aldehydes in the presence ofan acidic catalyst, the one or more phenolic compounds being selectedfrom phenols such as phenol, cresol, xylenol, resorcinol, bisphenol A,p-tert-butylphenol, and p-octylphenol, and naphthols such as α-naphthol,β-naphthol, 1,5-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene, andthe one or more aldehydes being selected from aldehyde sources such asformaldehyde, paraformaldehyde, and trioxane.

Examples of such a resin include a resin represented by the followinggeneral formula (a1), a resin represented by the following generalformula (a2), and the like.

(In the general formulae (a1) and (a2), R²¹ and R²² representindependently a hydroxyl group, a substituted or unsubstituted alkylgroup having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxylgroup having 1 to 6 carbon atoms, a substituted or unsubstitutedalkoxycarbonyl group having 2 to 10 carbon atoms, a substituted orunsubstituted aryl group having 6 to 14 carbon atoms, a substituted orunsubstituted glycidyl ether group, or a substituted or unsubstitutedalkyl glycidyl ether group (wherein the alkyl moiety has 1 to 6 carbonatoms), m2 is an integer from 0 to 6, provided that a plurality of R²¹may be either identical or different when m2 is an integer from 2 to 6,m3 is an integer from 0 to 4, provided that a plurality of R²² may beeither identical or different when m3 is an integer from 2 to 4, Zrepresents a methylene group, a substituted or unsubstituted alkylenegroup having 2 to 20 carbon atoms, a substituted or unsubstitutedarylene group having 6 to 14 carbon atoms, or a substituted orunsubstituted alkylene ether group, and m1 is an integer from 1 to 8,provided that a plurality of Z may be either identical or different whenm1 is an integer from 2 to 8, and m1, m2 and m3 satisfy relationships“1≦m1+m2≦8” and “1≦m1+m3≦8”.)

Examples of the unsubstituted alkyl group having 1 to 6 carbon atoms forR²¹ and R²² in the general formulae (a1) and (a2) include a methylgroup, an ethyl group, a n-propyl group, an i-propyl group, a n-butylgroup, a 2-methylpropyl group, a 1-methyl propyl group, a t-butyl group,and the like.

Examples of the unsubstituted alkoxyl group having 1 to 6 carbon atomsfor R²¹ and R²² include a methoxy group, an ethoxy group, a n-propoxygroup, an i-propoxy group, a n-butoxy group, a 2-methylpropoxy group, a1-methylpropoxy group, a t-butoxy group, a 2-propinyloxy group, and thelike.

Examples of the unsubstituted alkoxycarbonyl group having 2 to 10 carbonatoms for R²¹ and R²² include a methoxycarbonyl group, an ethoxycarbonylgroup, a n-propoxycarbonyl group, an i-propoxycarbonyl group, an-butoxycarbonyl group, a 2-methylpropoxycarbonyl group, a1-methylpropoxycarbonyl group, a t-butoxycarbonyl group, and the like.

Examples of the unsubstituted aryl group having 6 to 14 carbon atoms forR²¹ and R²² include a phenyl group, a naphthyl group, and the like.

Examples of the unsubstituted alkylglycidyl ether group for R²¹ and R²²include a methylglycidyl ether group, an ethylglycidyl ether group, apropylglycidyl ether group, a butylglycidyl ether group, and the like.

Examples of the unsubstituted alkylene group having 2 to 20 carbon atomsfor Z in the general formulae (a1) and (a2) include an ethylene group; apropylene group such as a 1,3-propylene group and a 1,2-propylene group;a tetramethylene group; a pentamethylene group; a hexamethylene group; a1-methyl-1,3-propylene group, a 2-methyl-1,3-propylene group, a2-methyl-1,2-propylene group, a 1-methyl-1,4-butylene group, a2-methyl-1,4-butylene group, and the like.

Examples of the unsubstituted arylene group having 6 to 14 carbon atomsfor Z include a phenylene group, a naphthylene group, an anthrylenegroup, a phenanthrylene group, and the like.

The number of carbon atom at the alkylene moiety in the alkylene ethergroup for Z is preferably in the range from 2 to 20. Specific examplesof the alkylene ether group include an ethylene ether group; a propyleneether group such as 1,3-propylene ether group and 1,2-propylene ethergroup; a tetramethylene ether group; a pentamethylene ether group; ahexamethylene ether group; and the like.

R²¹, R²² and Z in the general formulae (a1) and (a2) may have asubstituent. Examples of the substituent include a halogen atom, ahydroxyl group, an alkyl group having 1 to 9 carbon atoms, an aryl grouphaving 6 to 22 carbon atoms, and the like.

Examples of the halogen atom include a fluorine atom, a chlorine atom,bromine atom, an iodine atom, and the like.

Examples of the alkyl group having 1 to 9 carbon atoms include a methylgroup, an ethyl group, a n-propyl group, an i-propyl group, a n-butylgroup, a 2-methylpropyl group, a 1-methyl propyl group, a t-butyl group,and the like.

Examples of the unsubstituted aryl group having 6 to 22 carbon atomsinclude a phenyl group, a naphthyl group, and the like.

Specific examples of the resol resin include a resin obtained byreacting the above exemplified phenolic compound with the aboveexemplified aldehyde in the presence of an alkaline catalyst.

Examples of the acenaphthylene resin include a resin having a repeatingunit represented by the following general formula (a3), a resin having arepeating unit represented by the following general formula (a4), andthe like.

(In the general formulae (a3) and (a4), R²³ and R²⁴ representindependently a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted alkoxyl group having 1 to 6 carbon atoms, a substituted orunsubstituted alkoxycarbonyl group having 2 to 10 carbon atoms, or asubstituted or unsubstituted aryl group having 6 to 14 carbon atoms, andR²⁵ represents a hydrogen atom, a substituted or unsubstituted alkylgroup having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxygroup having 1 to 6 carbon atoms, a substituted or unsubstitutedalkoxycarbonyl group having 2 to 10 carbon atoms, or a substituted orunsubstituted aryl group having 6 to 14 carbon atoms.)

Examples of the unsubstituted alkyl group having 1 to 6 carbon atoms forR²³ to R²⁵ in the general formulae (a3) and (a4) include a methyl group,an ethyl group, a n-propyl group, an i-propyl group, a n-butyl group, a2-methylpropyl group, a 1-methyl propyl group, a t-butyl group, and thelike.

Examples of the unsubstituted alkoxyl group having 1 to 6 carbon atomsfor R²³ to R²⁵ include a methoxy group, an ethoxy group, a n-propoxygroup, an i-propoxy group, a n-butoxy group, a 2-methylpropoxy group, a1-methylpropoxy group, a t-butoxy group, a 2-propinyloxy group, and thelike.

Examples of the unsubstituted alkoxycarbonyl group having 2 to 10 carbonatoms for R²³ to R²⁵ include a methoxycarbonyl group, an ethoxycarbonylgroup, a n-propoxycarbonyl group, an i-propoxycarbonyl group, an-butoxycarbonyl group, a 2-methylpropoxycarbonyl group, a1-methylpropoxycarbonyl group, a t-butoxycarbonyl group, and the like.

Examples of the unsubstituted aryl group having 6 to 14 carbon atoms forR²³ to R²⁵ include a phenyl group, a naphthyl group, and the like.

Examples of the halogen atom for R²³ to R²⁴ in the general formulae (a3)to (a4) include a fluorine atom, a chlorine atom, bromine atom, aniodine atom, and the like.

R²³ to R²⁵ in the general formulae (a3) and (a4) may have a substituent.Examples of the substituent include a halogen atom, a hydroxyl group, analkyl group having 1 to 9 carbon atoms, an aryl group having 6 to 22carbon atoms, and the like.

Examples of the halogen atom include a fluorine atom, a chlorine atom,bromine atom, an iodine atom, and the like.

Examples of the alkyl group having 1 to 9 carbon atoms include a methylgroup, an ethyl group, a n-propyl group, an i-propyl group, a n-butylgroup, a 2-methylpropyl group, a 1-methyl propyl group, a t-butyl group,and the like.

Examples of the unsubstituted aryl group having 6 to 22 carbon atomsinclude a phenyl group, a naphthyl group, and the like.

Such resins may be obtained by reacting paraformaldehyde with a polymerof a compound having an acenaphthylene skeleton under acidic conditions.

Examples of the styrene resin or derivatives thereof include a resinhaving a structure represented by the following general formula (a5).

(In the general formula (a5), M represents a radically polymerizablemonomer, m is a positive integer, n is 0 or a positive integer, providedthat m and n satisfy the relationships “5≦m+n≦200” and “m/(m+n)≧0.5”,and R³¹ and R³² represent independently a hydrogen atom, an alkyl group,a hydroxyl group, an oxygen atom, an aryl group, or an ester group.)

The radically polymerizable monomer in the general formula (a5) is notparticularly limited and various compounds having a polymerizableunsaturated bond may be used. Specific examples include a styrene-basedmonomer such as styrene and α-methyl styrene; an acrylic monomer such asacrylonitrile, methacrylonitrile, (meth)acrylic acid, (meth)acrylic acidester including methyl(meth)acrylate, and acrylamide; a vinylether suchas ethyl vinylether; maleic anhydride, vinyl acetate, vinyl pyridine,and the like. In the specification, “(meth)acryl” means “acryl” or“methacryl”.

Examples of the alkyl group for R³¹ and R³² in the general formula (a5)include an alkyl group having 1 to 10 carbon atoms. Specific examplethereof includes a methyl group, an ethyl group, a n-propyl group, ani-propyl group, a n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, and the like.

Examples of the aryl group for R³¹ and R³² include an aryl group having6 to 30 carbon atoms. Specific example thereof includes a phenyl group,naphthyl group, and the like.

R³¹ and R³² are situated at the para position, the ortho position, orthe meta position.

The content of the structural unit derived from M (radicallypolymerizable monomer) which is a copolymerizable component in thegeneral formula (a5) is preferably less than 50% by mol based on 100% bymol of the total of structural units for the polymer.

A commercially available product may be used as the styrene resin orderivatives thereof (particularly a polyvinylphenol polymer). Examplesof the commercially available product include “Maruka Lyncur M” (whichis a poly-p-vinylphenol), “Lyncur MB” (which is a brominatedpoly-p-vinylphenol), “Lyncur CMM” (which is a p-vinylphenol/methylmethacrylate copolymer), “Lyncur CHM” (which is ap-vinylphenol/2-hydroxyethyl methacrylate copolymer), “Lyncur CST”(which is a p-vinylphenol/styrene copolymer) that are manufactured byMaruzen Petrochemical Co., Ltd.; and the like.

The polystyrene-reduced weight average molecular weight (hereinafter maybe referred to as “Mw”) determined by gel permeation chromatography(GPC) of the resin (A1) is preferably in the range from 500 to 100,000,more preferably from 1,000 to 50,000, and further preferably from 1,200to 40,000.

Additionally, the ratio (Mw/Mn) of the Mw to the polystyrene-reducednumber average molecular weight (hereinafter may be referred to as “Mn”)of the resin (A) determined by GPC of the resin (A1) is normally in therange from 1 to 5, and more preferably from 1 to 3.

The resist underlayer film-forming composition of the embodiment of thepresent invention may contain only one resin (A1) or two or more typesthereof

(A2) Compound Having Fullerene Skeleton

The resist underlayer film-forming composition of the embodiment of thepresent invention may contain a compound having a fullerene skeleton(hereinafter may be referred to as “compound (A2)”) as the basecomponent. Examples of the compound (A2) include fullerenes andfullerene derivatives.

Examples of the fullerenes include a C₃₆ fullerene, a C₆₀ fullerene, aC₇₀ fullerene, a C₇₆ fullerene, a C₇₈ fullerene, a C₈₂ fullerene, a C₈₄fullerene, a C₉₀ fullerene, a C₉₆ fullerene, higher fullerenes havingmore than 96 carbon atoms and having a maximum aggregate diameter of 30nm or less, and the like. Among these, a C₆₀ fullerene, a C₇₀ fullerene,a C₇₆ fullerene, a C₈₂ fullerene, and the like are preferably used.

These fullerenes can be synthesized by a known method. The C₃₆ fullerenecan be synthesized by the method disclosed in “New Diamond” (Vol. 16,No. 2, 2000, pp. 30-31). The C₆₀ fullerene, the C₇₀ fullerene, the C₇₆fullerene, the C₇₈ fullerene, the C₈₂ fullerene, the C₈₄ fullerene, theC₉₀ fullerene, and the C₉₆ fullerene can be synthesized by the arcdischarge method disclosed in “J. Phy. Chem.” (94, 1990, p. 8634), orthe oven laser method disclosed in “Z. Phys. D” (40, 1997, p. 414). Ahigher fullerene having more than 96 carbon atoms and having a maximumaggregate diameter of 30 nm or less can be obtained as a byproduct whensynthesizing a fullerene using an arc discharge method. Examples ofcommercially available products of the C₆₀ fullerene and the C₇₀fullerene include products manufactured by Frontier Carbon Corporation,Materials Technologies Research (MTR) Limited, and the like. Examples ofcommercially available products of the C₇₆ fullerene, the C₇₈ fullerene,and the C₈₄ fullerene include products manufactured by MaterialsTechnologies Research (MTR) Limited, and the like. A mixture offullerenes that differ in the number of carbon atoms can be used. Forexample, a mixture of C₆₀/C₇₀ fullerenes manufactured by Frontier CarbonCorporation or Materials Technologies Research (MTR) Limited may beused.

Examples of the fullerene derivatives include a functionalgroup-containing fullerene derivative and a heteroring-containingfullerene derivative. The functional group-containing fullerenederivative includes, on the surface of a fullerene, a functional groupsuch as an alkyl group having 1 to 6 carbon atoms, an alkenyl grouphaving 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms,a carboxyl group, a hydroxyl group, an epoxy group, and an amino group.The amino group is represented by —NR¹ ₂ (wherein R¹ represents ahydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenylgroup having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbonatoms, or a polyether chain having a molecular weight of 30 to 50,000).When R¹ is a polyether chain having a molecular weight of 30 to 50,000,the end of the polyether chain may be a hydroxyl group or an alkoxygroup having 1 to 6 carbon atoms.

The fullerene derivative may be synthesized by the epoxidation reactiondisclosed in “Science” 548 (1991) and “J. Am. Chem. Soc.” 1103 (1992),the primary or secondary amine addition reaction disclosed in “Angew.Chem. Int. Ed. Engl.” 1309 (1991), the Diels-Alder reaction disclosed in“J. Am. Chem. Soc.” 7301 (1992), the polyhydroxylation reactiondisclosed in “J. Chem. Soc., Chem. Commun.” 1791 (1992), or the like.

On the other hand, the heteroring-containing fullerene derivative is afullerene derivative in which a group having a heteroring is bonded to afullerene. The group having a heteroring is preferably a group having afuran ring and/or a thiophene ring. The heteroring-containing fullerenederivative can be obtained by Diels-Alder reaction of a fullerene and acompound having a heteroring such as furan ring. Specifically, afullerene and a compound having a heteroring (e.g., furfuryl alcohol,furoyl chloride, carboxylfuran, or furfurylamine) can be subjected toDiels-Alder reaction while stirring the fullerene and the compound in asolvent which dissolves the both compounds. It is preferable to subjectthe fullerene and the compound having a heteroring to Diels-Alderreaction at a temperature ranging 30° C. to 100° C. so that the molarratio of the fullerene to the heteroring is less than 1.

Specific examples of the fullerene derivatives include the fullerenederivatives disclosed in paragraphs [0044] to [0046] of Japanese PatentApplication Publication (KOKAI) No. 2004-264710, the fullerenederivatives disclosed in Japanese Patent Application Publication (KOKAI)No. 2008-164806, the fullerene derivatives disclosed in WO08/062888, thefullerene derivatives disclosed in Japanese Patent ApplicationPublication (KOKAI) No. 2008-129423, and the fullerene derivativesdisclosed in Japanese Patent Application Publication (KOKAI) No.2006-227391.

The resist underlayer film-forming composition of the embodiment of thepresent invention may contain only one resin (A2) or two or more typesthereof

(B) Crosslinking Agent

The crosslinking agent (hereinafter may be referred to as “crosslinkingagent (B)”) has a partial structure represented by the following generalformula (i). Specifically, the structural formula of a compound used asthe crosslinking agent (B) includes at least the structure representedby the general formula (i). The crosslinking agent (B) may be a compoundhaving the structure represented by the general formula (i).

In the resist underlayer film-forming composition of the embodiment ofthe present invention, when the crosslinking agent (B) reacts with thebase component (A), a methylene moiety positioned between the aromaticrings is obtained. Since the hydrogen atom of the methylene moiety iseasily oxidized, a new crosslinking point is formed. The newcrosslinking point is further crosslinked, so that the hydrogen atomcontent in the entire material decreases. It is considered that thebending resistance of the resulting resist underlayer film is thusimproved.

(In the general formula (i), X represents an oxygen atom, a sulfur atom,or —NR— (wherein R represents a hydrogen atom, an alkyl group having 1to 9 carbon atoms, or an aryl group having 6 to 30 carbon atoms),provided that a plurality of X may be either identical or different whena plurality of X are present, n₁ is an integer from 1 to 6, and R¹represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, provided that a pluralityof R¹ may be either identical or different when a plurality of R¹ arepresent.)

Examples of the alkyl group having 1 to 9 carbon atoms for R in —NR— ofX in the general formula (i) include a methyl group, an ethyl group, an-propyl group, an i-propyl group, a n-butyl group, a 2-methylpropylgroup, a 1-methyl propyl group, a t-butyl group, and the like.

Additionally, examples of the aryl group having 6 to 30 carbon atoms forR include a phenyl group, a naphthyl group, a methylphenyl group, anethylphenyl group, and the like.

Examples of the alkyl group having 1 to 9 carbon atoms for R¹ in thegeneral formula (i) include a methyl group, an ethyl group, a n-propylgroup, an i-propyl group, a n-butyl group, a 2-methylpropyl group, a1-methyl propyl group, a t-butyl group, and the like.

Additionally, examples of the aryl group having 6 to 30 carbon atoms forR¹ include a phenyl group, a naphthyl group, a methylphenyl group, anethylphenyl group, and the like.

Moreover, n₁ in the general formula (i) is preferably an integer from 1to 6, and is more preferably an integer from 1 to 3.

Examples of the crosslinking agent (B) having the above structureinclude a compound represented by the following general formula (b1-1),a compound represented by the following general formula (b2), and thelike.

(In the general formula (b1-1), X represents an oxygen atom, a sulfuratom, or —NR— (wherein R represents a hydrogen atom, an alkyl grouphaving 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbonatoms), provided that a plurality of X may be either identical ordifferent when a plurality of X are present, n₂ is an integer from 1 to5, n₃ is independently an integer from 1 to 4, m is independently 0 or1, R¹ represents a hydrogen atom, an alkyl group having 1 to 9 carbonatoms, or an aryl group having 6 to 30 carbon atoms, provided that aplurality of R¹ may be either identical or different when a plurality ofR¹ are present, R² represents a hydrogen atom, a hydroxyl group, analkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to 22carbon atoms, provided that a plurality of R² may be either identical ordifferent when a plurality of R² are present, and R³ represents a singlebond, an oxygen atom, an ester group, a carbonyl group, a chain-likehydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbongroup having 3 to 30 carbon atoms, an aromatic hydrocarbon group having6 to 30 carbon atoms, a nitrogen atom, a sulfur atom, or an(n₂+1)-valent group formed by arbitrarily combining any one of thesegroups and atoms.)

(In the general formula (b2), X represents an oxygen atom, a sulfuratom, or —NR— (wherein R represents a hydrogen atom, an alkyl grouphaving 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbonatoms), provided that a plurality of X may be either identical ordifferent when a plurality of X are present, n₄ is an integer from 1 to5, m is 0 or 1, R¹ represents a hydrogen atom, an alkyl group having 1to 9 carbon atoms, or an aryl group having 6 to 30 carbon atoms,provided that a plurality of R¹ may be either identical or differentwhen a plurality of R¹ are present, and R² represents a hydrogen atom, ahydroxyl group, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 22 carbon atoms.)

In the general formula (b1-1), R¹ and X are respectively the same asdefined for R¹ and X in the general formula (i).

Examples of the alkyl group having 1 to 9 carbon atoms for R² in thegeneral formula (b1-1) include a methyl group, an ethyl group, an-propyl group, an i-propyl group, a n-butyl group, a 2-methylpropylgroup, a 1-methyl propyl group, a t-butyl group, and the like.

Additionally, examples of the aryl group having 6 to 22 carbon atoms forR² include a phenyl group, a naphthyl group, a methylphenyl group, anethylphenyl group, and the like.

In the general formula (b1-1), n₂ is preferably an integer from 1 to 5,and is more preferably an integer from 1 to 2.

Moreover, n₃ is preferably an integer from 1 to 4, and is morepreferably an integer from 1 to 3.

Examples of the chain-like hydrocarbon group having 1 to 30 carbon atomsfor R³ in the general formula (b1-1) include a (n₂+1)-valent group (n₂:1 to 5) derived from a methyl group, an ethyl group, a n-propyl group,an i-propyl group, a n-butyl group, a 2-methylpropyl group, a1-methylpropyl group, a t-butyl group, a vinyl group, an ethynyl group,and the like.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atomsfor R³ in the general formula (b1-1) include a (n₂+1)-valent groupderived from a cyclopropyl group, a cyclobutyl group, a cyclopentylgroup, a cyclohexyl group, a methylcyclohexyl group, and the like.

Examples of the aromatic hydrocarbon group having 6 to 30 carbon atomsfor R³ in the general formula (b1-1) include a (n₂+1)-valent groupderived from a phenyl group, a naphthyl group, an anthracenyl group, apyrene group, a coronene group, and the like.

R³ in the general formula (b1-1) may have a substituent. Examples of thesubstituent include a halogen atom, a hydroxyl group, an alkyl grouphaving 1 to 9 carbon atoms, an aryl group having 6 to 22 carbon atoms,and the like.

Examples of the alkyl group having 1 to 9 carbon atoms include a methylgroup, an ethyl group, a n-propyl group, an i-propyl group, a n-butylgroup, a 2-methylpropyl group, a 1-methyl propyl group, a t-butyl group,and the like.

Examples of the aryl group having 6 to 22 carbon atoms include a phenylgroup, a naphthyl group, a methylphenyl group, an ethylphenyl group,

Examples of the (n₂+1)-valent group by arbitrarily combining an oxygenatom, an ester group, a carbonyl group, a chain-like hydrocarbon grouphaving 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbonatoms, a nitrogen atom, or a sulfur atom for R³ in the general formula(b1-1) include a (n₂+1)-valent organic group derived from any of thestructures represented by the following general formulae (R-1) to (R-4).

(In the general formulae (R-1) to (R-4), R⁴⁰, R⁴², and R⁴³ representindependently a substituted or unsubstituted monovalent hydrocarbongroup having 1 to 10 carbon atoms, provided that a plurality of R⁴° maybe either identical or different when a plurality of R⁴° are present, aplurality of R⁴² may be either identical or different when a pluralityof R⁴² are present, and a plurality of R⁴³ may be either identical ordifferent when a plurality of R⁴³ are present, R⁴¹ representsindependently a single bond or a substituted or unsubstituted divalenthydrocarbon group having 1 to 10 carbon atoms, provided that a pluralityof R⁴¹ may be either identical or different when a plurality of R⁴¹ arepresent, n6 is an integer from 1 to 6, n7 is an integer from 0 to 5, n8is an integer from 1 to 4, n9 is an integer from 0 to 5, n10 is aninteger from 1 to 6, and Y represents an oxygen atom, an ester group, ora carbonyl group.)

Examples of the unsubstituted monovalent hydrocarbon group having 1 to10 carbon atoms for R⁴⁰, R⁴², and R⁴³ in the general formulae (R-1) to(R-4) include a methyl group, an ethyl group, a n-propyl group, ani-propyl group, a n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, and the like.

Examples of the unsubstituted divalent hydrocarbon group having 1 to 10carbon atoms for R⁴¹ in the general formulae (R-2) to (R-3) include amethylene group, an ethylene group, a 1,2-propylene group, a1,3-propylene group, a tetramethylene group, a pentamethylene group, ahexamethylene group, a heptamethylene group, an octamethylene group, andthe like.

R⁴⁰ to R⁴³ in the general formulae (R-1) to (R-4) may have asubstituent. Examples of the substituent include a halogen atom, ahydroxyl group, an alkyl group having 1 to 9 carbon atoms, an aryl grouphaving 6 to 22 carbon atoms, and the like.

Examples of the halogen atom include a fluorine atom, a chlorine atom,bromine atom, an iodine atom, and the like.

Examples of the alkyl group having 1 to 9 carbon atoms include a methylgroup, an ethyl group, a n-propyl group, an i-propyl group, a n-butylgroup, a 2-methylpropyl group, a 1-methyl propyl group, a t-butyl group,and the like.

Examples of the unsubstituted aryl group having 6 to 22 carbon atomsinclude a phenyl group, a naphthyl group, and the like.

In the general formula (b2), R¹, R² and X are respectively the same asdefined for R¹, R² and X in the general formula (b1-1).

Moreover, n₄ in the general formula (b2) is an integer from 1 to 5, andis more preferably an integer from 1 to 3.

Additionally, the crosslinking agent (B) is preferably a compoundrepresented by the following general formula (b1-2).

(In the general formula (b1-2), n₅ is an integer from 1 to 5, R⁵represents independently a hydrogen atom, an alkyl group having 1 to 9carbon atoms, or an aryl group having 6 to 30 carbon atoms, and R⁶represents a single bond, an oxygen atom, an ester group, a carbonylgroup, a chain-like hydrocarbon group having 1 to 30 carbon atoms, analicyclic hydrocarbon group having 3 to 30 carbon atoms, an aromatichydrocarbon group having 6 to 30 carbon atoms, a nitrogen atom, a sulfuratom, or an (n₅+1)-valent group formed by arbitrarily combining any oneof these groups and atoms.)

Examples of the alkyl group having 1 to 9 carbon atoms for R⁵ in thegeneral formula (b1-2) include a methyl group, an ethyl group, an-propyl group, an i-propyl group, a n-butyl group, a 2-methylpropylgroup, a 1-methyl propyl group, a t-butyl group, and the like.

Additionally, examples of the aryl group having 6 to 30 carbon atoms forR⁵ include a phenyl group, a naphthyl group, a methylphenyl group, anethylphenyl group, and the like.

Examples of the chain-like hydrocarbon group having 1 to 30 carbon atomsfor R⁶ in the general formula (b1-2) include a (n₅+1)-valent group (n₅:1 to 5) derived from a methyl group, an ethyl group, a n-propyl group,an i-propyl group, a n-butyl group, a 2-methylpropyl group, a1-methylpropyl group, a t-butyl group, a vinyl group, an ethynyl group,and the like.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atomsfor R⁶ in the general formula (b1-2) include a (n₂+1)-valent groupderived from a cyclopropyl group, a cyclobutyl group, a cyclopentylgroup, a cyclohexyl group, a methylcyclohexyl group, and the like.

Examples of the aromatic hydrocarbon group having 6 to 30 carbon atomsfor R⁶ in the general formula (b1-2) include a (n₅+1)-valent groupderived from a phenyl group, a naphthyl group, an anthracenyl group, apyrene group, a coronene group, and the like.

In the general formula (b1-2), n₅ is an integer of 1 to 5, and ispreferably an integer of 1 to 2.

Examples of the (n₄+1)-valent group by arbitrarily combining an oxygenatom, an ester group, a carbonyl group, a chain-like hydrocarbon grouphaving 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbonatoms, a nitrogen atom, or a sulfur atom for R⁶ in the general formula(b1-2) include a (n₄+1)-valent organic group derived from any of thestructures represented by the above-described general formulae (R-1) to(R-4).

A compound represented by the following general formula (b1-3) isparticularly preferred as the crosslinking agent (B).

(In the general formula (b1-3), R⁸ represents independently a hydrogenatom, an alkyl group having 1 to 9 carbon atoms, or an aryl group having6 to 30 carbon atoms, and R⁹ represents a single bond, an oxygen atom,an ester group, a carbonyl group, a chain-like hydrocarbon group having1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms,a sulfur atom, —NR— (wherein R represents a hydrogen atom, an alkylgroup having 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbonatoms), or a divalent group formed by arbitrarily combining these groupsand atoms.)

Examples of the alkyl group having 1 to 9 carbon atoms for R⁸ in thegeneral formula (b1-3) include a methyl group, an ethyl group, an-propyl group, an i-propyl group, a n-butyl group, a 2-methylpropylgroup, a 1-methyl propyl group, a t-butyl group, and the like.

Additionally, examples of the aryl group having 6 to 30 carbon atoms forR⁸ include a phenyl group, a naphthyl group, a methylphenyl group, anethylphenyl group, and the like.

Examples of the divalent chained hydrocarbon group having 1 to 30 carbonatoms for R⁹ in the general formula (b1-3) include a linear alkylenegroup such as a methylene group, an ethylene group, a 1,2-propylenegroup, a 1,3-propylene group, a tetramethylene group, a pentamethylenegroup, a hexamethylene group, a heptamethylene group, an octamethylenegroup, a nonamethylene group, a decamethylene group, an undecamethylenegroup, a dodecamethylene group, a tridecamethylene group, atetradecamethylene group, a pentadecamethylene group, ahexadecamethylene group, a heptadecamethylene group, anoctadecamethylene group, a nonadecamethylene group, and an icosylenegroup; and a branched alkylene group such as a 1-methyl-1,3-propylenegroup, a 2-methyl-1,3-propylene group, a 2-methyl-1,2-propylene group, a1-methyl-1,4-butylene group, a 2-methyl-1,4-butylene group, amethylidene group, an ethylidene group, a propylidene group, and a2-propylidene group; and the like.

Examples of the divalent alicyclic hydrocarbon group having 3 to 30carbon atoms for R⁹ in the general formula (b1-3) include a monocycliccycloalkylene group such as a 1,3-cyclobutylene group, a1,3-cyclopentylene group, a 1,4-cyclohexylene group, and a1,5-cyclooctylene group; a polycyclic cycloalkylene group such as a1,4-norbornylene group, a 2,5-norbornylene group, a 1,5-adamantylenegroup, and 2,6-adamantylene group; and the like.

Examples of the divalent aromatic hydrocarbon group having 6 to 30carbon atoms for R⁹ in the general formula (b1-3) include an arylenegroup such as a phenylene group, a tolylene group, a naphthylene group,a phenanthrylene group, and an anthrylene group; and the like.

Examples of the bivalent group by arbitrarily combining an oxygen atom,an ester group, a carbonyl group, a chain-like hydrocarbon group having1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms,a nitrogen atom, or a sulfur atom for R⁹ in the general formula (b1-3)include a bivalent organic group derived from any of the structuresrepresented by the above-described general formulae (R-1) to (R-4).

Specific examples of the crosslinking agent (B) includebenzenedimethanol, benzenetrimethanol, benzenetetramethanol,benzenepentamethanol, benzenehexamethanol, biphenyldimethanol,biphenyltrimethanol, biphenyltetramethanol, biphenylpentamethanol,biphenylhexamethanol, hydroxybiphenyldimethanol,hydroxybiphenyltrimethanol, hydroxybiphenyltetramethanol,hydroxybiphenylpentamethanol, hydroxybiphenylhexamethanol,dihydroxybiphenyldimethanol, dihydroxybiphenyltrimethanol,dihydroxybiphenyltetramethanol, dihydroxybiphenylpentamethanol,dihydroxybiphenylhexamethanol, the following compounds represented byformulae (B1) to (B22), and the like.

The crosslinking agent (B) may be used singly or in combination of twoor more types thereof.

The crosslinking agent (B) is used in an amount of normally 500 parts orless by mass, and preferably 100 parts or less by mass based on 100parts by mass of the base component (A) according to the resistunderlayer film-forming composition.

Other Crosslinking Agent

The resist underlayer film-forming composition of the embodiment of thepresent invention may contain other crosslinking agents other than thecrosslinking agent (B).

Examples of the other crosslinking agents include a polynuclear phenol,commercially available curing agents, and the like. Specific examples ofthe other crosslinking agents include the compounds disclosed inparagraphs [0085] and [0086] of Japanese Patent Application Publication(KOKAI) No. 2004-168748, and the like.

The other crosslinking agents may be used singly or in combination oftwo or more types thereof. The polynuclear phenol and curing agent maybe used in combination.

The other crosslinking agent is used in an amount of normally 500 partsor less by mass, and preferably 100 parts or less by mass based on 100parts by mass of the base component (A) according to the resistunderlayer film-forming composition.

(C) Solvent

The resist underlayer film-forming composition of the embodiment of thepresent invention is one containing the base component (A) andcrosslinking agent (B). And the composition is normally a liquidcomposition containing a solvent that dissolves the base component (A)(hereinafter may be referred to as “solvent (C)”).

The solvent (C) is not particularly limited as long as the solvent (C)dissolves the base component (A). Examples of the solvent (C) includethe compounds disclosed in paragraphs [0070] to [0073] of JapanesePatent Application Publication (KOKAI) No. 2004-168748, and the like.

Propylene glycol monomethyl ether, ethylene glycol monoethyl etheracetate, ethyl lactate, n-butyl acetate, ethyl 3-ethoxypropionate,methyl 3-methoxypropionate, ketones such as 2-heptanone andcyclohexanone, γ-butyrolactone, and the like are preferable as thesolvent (C).

The solvent (C) may be used singly or in combination of two or moretypes thereof.

The solvent (C) is used in such an amount that the resulting compositionhas a solid content of normally 1% to 80% by mass, preferably 3% to 40%by mass, and more preferably 5% to 30% by mass.

The resist underlayer film-forming composition of the embodiment of thepresent invention may optionally include (D) an acid generator, (E) apromoter, and (F) an additive as long as the desired effects of theinvention are not impaired. The resist underlayer film-formingcomposition preferably includes (E) a promoter.

(D) Acid Generator

The acid generator (D) is a component which generates an acid uponexposure or heating. When the resist underlayer film-forming compositionof the embodiment of the present invention contains the acid generator(D), the acid generator (D) ensures that the molecular chains of theresin are effectively crosslinked at a relatively low temperatureincluding room temperature.

Examples of the acid generator capable of generating an acid uponexposure (hereinafter referred to as “photoacid generator”) includecompounds disclosed in paragraphs [0077] to [0081] of Japanese PatentApplication Publication (KOKAI) No. 2004-168748, and the like.

Among the compounds exemplified, diphenyliodoniumtrifluoromethanesulfonate, diphenyliodoniumnonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate,diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium10-camphorsulfonate, diphenyliodonium naphthalenesulfonate,bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate,bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate,bis(4-t-butylphenyl)iodonium n-dodecylbenzenesulfonate,bis(4-t-butylphenyl)iodonium 10-camphorsulfonate,bis(4-t-butylphenyl)iodonium naphthalenesulfonate, and the like arepreferable.

The photoacid generator may be used singly or in combination of two ormore types thereof.

Examples of the acid generator capable of generating an acid uponheating (hereinafter referred to as “thermal acid generator”) include2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyltosylate, alkyl sulfonates, and the like.

The thermal acid generator may be used singly or in combination of twoor more types thereof. The photoacid generator and thermal acidgenerator may be used in combination.

The acid generator (D) is used in an amount of normally 5,000 parts orless by mass, preferably 0.1 to 1,000 parts by mass, and more preferably0.1 to 100 parts by mass based on 100 parts by mass of the basecomponent (A) in the resist underlayer film-forming composition.

(E) Promoter

The promoter (E) is a one-electron oxidizing agent that leads to asufficient dehydrogenation reaction necessary for oxidativecrosslinking, and the like. The term “one-electron oxidizing agent” usedherein refers to an oxidizing agent that undergoes one-electrontransfer. When cerium(IV) ammonium nitrate is used, the cerium(IV) ionis converted into a cerium(III) ion upon acquisition of one electron. Aradical oxidizing agent (e.g., halogen) is converted into an anion uponacquisition of one electron. A phenomenon in which the oxidation targetsubstance (e.g., substrate or catalyst) is oxidized by removing oneelectron from the oxidation target substance is referred to as“one-electron oxidation”, and a component that receives one electron isreferred to as “one-electron oxidizing agent”.

Typical examples of the one-electron oxidizing agent include (a) a metalcompound, (b) a peroxide, (c) a diazo compound, (d) a halogen or ahalogen acid, and the like.

Examples of the metal compound (a) include metal compounds that includecerium, lead, silver, manganese, osmium, ruthenium, vanadium, thallium,copper, iron, bismuth, or nickel. Specific examples of the metalcompound (a) include (a1) a cerium salt (tetravalent cerium salts) suchas cerium (IV) ammonium nitrate (CAN; cerium (IV) ammonium hexanitrate),cerium (IV) acetate, cerium (IV) nitrate, and cerium (IV) sulfate, (a2)a lead compound (tetravalent lead compounds) such as lead tetraacetateand lead (IV) oxide, (a3) a silver compound such as silver (I) oxide,silver (II) oxide, silver carbonate (Fetizon reagent), and silvernitrate, (a4) a manganese compound such as permanganates, activemanganese dioxide, and manganese (III) salts, (a5) an osmium compoundsuch as osmium tetroxide, (a6) a ruthenium compound such as rutheniumtetroxide, (a7) a vanadium compound such as VOCl₃, VOF₃, V₂O₅, NH₄VO₃,and NaVO₃, (a8) a thallium compound such as thallium (III) acetate,thallium (III) trifluoroacetate, and thallium (III) nitrate, (a9) acopper compound such as copper (II) acetate, copper (II)trifluoromethanesulfonate, copper (II) trifluoroborate, copper (II)chloride, and copper (I) acetate, (a10) an iron compound such as iron(III) chloride and potassium hexacyanoferrate (III), (a11) a bismuthcompound such as sodium bismuthate, (a12) a nickel compound such asnickel peroxide, and the like.

Examples of the peroxide (b) include a peroxyacid such as peracetic acidand m-chloroperbenzoic acid, hydrogen peroxide; a hydroxyperoxide suchas an alkyl hydroxyperoxide (e.g., t-butyl hydroperoxide); a diacylperoxide; a peroxyacid ester; a peroxyketal; a peroxydicarbonate; adialkyl peroxide; a peroxyketone; and the like.

Examples of the diazo compound (c) include 2,2′-azobisisobutyronitrileand the like.

Examples of the halogen or the halogen acid (d) include halogensselected from chlorine, bromine, and iodine; a perhalogen acid; ahalogen acid; a halous acid; a hypohalous acid; salts thereof, and thelike. Examples of the halogen capable of forming the halogen acidinclude chlorine, bromine, and iodine. Examples of the salts of thehalogen acids include sodium perchlorate, sodium bromate, and the like.

Among these, the peroxide (b) and diazo compound (c) are preferable, andm-chloroperbenzoic acid, t-butyl hydroperoxide, and2,2′-azobisisobutyronitrile are particularly preferred. When thesecompounds are used as the one-electron oxidizing agent, a metal residuedoes not adhere to the substrate, being favorable.

The promoter (E) including the one-electron oxidizing agent may be usedsingly or in combination of two or more types thereof.

The promoter (E) is used in an amount of normally 1,000 parts or less bymass, preferably in the range from 0.01 to 500 parts by mass, and morepreferably from 0.1 to 100 parts by mass based on 100 parts by mass ofthe base component (A) according to the resist underlayer film-formingcomposition.

(F) Additives

Examples of the additive (F) include a binder resin, a radiationabsorber, a surfactant, and the like.

Specific examples of the additive (F) include compounds disclosed inparagraphs [0088] to [0093] of Japanese Patent Application Publication(KOKAI) No. 2004-168748, and the like.

A thermoplastic resin or a thermosetting resin (excluding the resin(A1)) may be used as the binder resin. The thermoplastic resin is acomponent which provides the resist underlayer film with flowability,mechanical properties, and the like. On the other hand, thethermosetting resin is a component which becomes insoluble in thesolvent upon curing due to heating, and prevents intermixing between theresist underlayer film and a resist film formed on the resist underlayerfilm. The thermosetting resin may preferably be used as the binderresin. A urea resin, a melamine resin, an aromatic hydrocarbon resin, orthe like is preferable as the thermosetting resin.

The binder resin may be used singly or in combination of two or moretypes thereof

The binder resin is used in an amount of normally 20 parts or less bymass, and preferably 10 parts or less by mass based on 100 parts by massof the base component (A) according to the resist underlayerfilm-forming composition.

The radiation absorber is used in an amount of normally 100 parts orless by mass, and preferably 50 parts or less by mass based on 100 partsby mass of the base component (A) according to the resist underlayerfilm-forming composition.

The surfactant is a component which improves the applicability,striation, wettability, developability, and the like.

The surfactant may be used singly or in combination of two or more typesthereof.

The surfactant is used in an amount of normally 15 parts or less bymass, and preferably 10 parts or less by mass based on 100 parts by massof the base component (A) according to the resist underlayerfilm-forming composition.

The resist underlayer film-forming composition of the embodiment of thepresent invention may further include a preservative, an anti-foamingagent, an adhesion improver, and the like.

According to the resist underlayer film-forming composition of theembodiment of the present invention, a resist underlayer film can easilybe formed which exhibits excellent etching resistance, and suppresses asituation in which the underlayer film pattern is bent when etching thesubstrate.

Additionally, the resist underlayer film formed using the resistunderlayer film-forming composition exhibits excellent etchingresistance, and suppresses a situation in which the underlayer filmpattern is bent when etching the substrate even when transferring a finepattern. Therefore, the resist underlayer film exhibits an excellentpattern transfer capability and excellent etching selectivity during adry etching process (i.e., the resist underlayer film is rarelyover-etched, and the resist pattern can be transferred to the substratewith good reproducibility). Since the underlayer film pattern is notbent when etching the substrate, an increase in yield is expected to beachieved during microfabrication employed in a lithographic process(particularly the production of integrated circuit devices).

2. Pattern Forming Method

The pattern forming method of the embodiment of the present inventionincludes (1) a resist underlayer film-forming process in which aspecific resist underlayer film-forming composition is used to form aresist underlayer film on a substrate (hereinafter may be referred to as“process (1)”), (1′) an intermediate layer-forming process in which anintermediate layer is formed on the resist underlayer film (hereinaftermay be referred to as “process (1′)”), (2) a resist film-forming processin which a resist composition is coated onto the resist underlayer filmon which the intermediate layer is formed to form a resist film(hereinafter may be referred to as “process (2)”), (3) an exposureprocess in which the resist film is subjected to exposing by selectivelyapplying radiation (hereinafter may be referred to as “process (3)”),(4) a resist pattern-forming process in which the exposed resist film issubjected to developing to form a resist pattern (hereinafter may bereferred to as “process (4)”), and (5) a pattern-forming process inwhich the intermediate layer, the resist underlayer film, and thesubstrate are dry-etched using the resist pattern as a mask to form agiven pattern on the substrate (hereinafter may be referred to as“process (5)”).

In the process (1), the resist underlayer film is formed on thesubstrate.

Specifically, the resist underlayer film can be formed by a step forapplying the resist underlayer film-forming composition to the substrateto form a coating film, and a step for heating the film together withthe substrate to form a resist underlayer film on the substrate. Thedescription given above in connection with the resist underlayerfilm-forming composition of the embodiment of the present invention maybe applied to the resist underlayer film-forming composition used in theprocess (1).

A silicon wafer, an aluminum-coated wafer, or the like can be used asthe substrate.

The coating method of the resist underlayer film-forming composition isnot particularly limited and the composition may be applied to thesubstrate by an appropriate method (e.g., spin coating, cast coating, orroll coating).

The coating film is normally heated in air.

The heating temperature is normally in the range from 300° C. to 500°C., and preferably from 350° C. to 450° C. If the heating temperature islower than 300° C., oxidative crosslinking may not sufficiently proceed,so that the underlayer film may not exhibit the desired properties.

The heating time is in the range from 30 to 1,200 seconds, andpreferably from 60 to 600 seconds.

The oxygen concentration when curing the coating film is preferably 5%or more by volume. If the oxygen concentration when curing the coatingfilm is low, oxidative crosslinking may not sufficiently proceed, sothat the underlayer film may not exhibit the desired properties.

The film may be preheated at a temperature between 60° C. and 250° C.before heating the coating film at a temperature ranging from 300° C. to500° C.

The preheating time is not particularly limited and is preferably in therange from 10 to 300 seconds and more preferably from 30 to 180 seconds.

When the preheating is conducted, the solvent can be volatilized (i.e.,the film can be made dense), and the dehydrogenation reaction canproceed efficiently.

In the process (1), when the coating film is heated, the film isnormally cured to obtain a resist underlayer film. On the other hand,when a specific photocuring agent (crosslinking agent) is added to theresist underlayer film-forming composition and the process includes anexposing step, the resist underlayer film may be formed by applyingradiation to the heated film. The radiation used to cure the coatingfilm is appropriately selected from visible rays, ultraviolet rays, deepultraviolet rays, X-rays, electron beams, γ-rays, molecular beams, ionbeams, and the like depending on the type of acid generator included inthe resist underlayer film-forming composition.

The thickness of the resist underlayer film formed by the process (1) isnormally in the range from 0.1 to 5 μm.

The hydrogen content in the resist underlayer film is in the range from0 to 50 atom %, and preferably from 0 to 35 atom %. The hydrogen contentin the resist underlayer film is measured by the method described inExamples.

In the process (1′), the intermediate layer (intermediate film) isformed on the resist underlayer film.

The intermediate layer enhances the functions of the resist underlayerfilm and/or the resist film, or provides the resist underlayer filmand/or the resist film with an additional function when forming a resistpattern. The antireflective function of the resist underlayer film canbe enhanced by forming an antireflective film as the intermediate layer.

The intermediate layer can be formed using an organic compound or aninorganic oxide. Examples of the organic compound include “DUV-42”,“DUV-44”, “ARC-28”, and “ARC-29” manufactured by Brewer Science; “AR-3”,and “AR-19” manufactured by Rohm and Haas; and the like. Examples of theinorganic oxide include “NFC SOG01”, “NFC SOG04”, and “NFC SOG080”manufactured by JSR Corporation; a polysiloxane, titanium oxide,alumina, and tungsten oxide, formed by CVD; and the like.

The forming method of the intermediate layer is not particularly limitedand the intermediate layer can be formed by an arbitrary method such asa coating method and CVD. It is preferable to form the intermediatelayer by a coating method. When using a coating method, the intermediatelayer can be formed continuously with the resist underlayer film.

The thickness of the intermediate layer is not particularly limited andmay be appropriately selected depending on the desired functions. It ispreferably in the range from 10 to 3,000 nm and more preferably from 20to 300 nm.

In the process (2), the resist film is formed on the resist underlayerfilm (on which the intermediate layer is formed) using the resistcomposition. Specifically, when the resist composition is coated on theresist underlayer film so that the resulting resist film has a giventhickness, and the film is subjected to prebaking, a solvent in thecoating is volatilized to form the resist film.

Examples of the resist composition include a positive-tone ornegative-tone chemically-amplified resist composition containing aphotoacid generator; a positive-tone resist composition containing analkali-soluble resin and a quinondiazide photosensitizer; anegative-tone resist composition containing an alkali-soluble resin anda crosslinking agent; and the like.

The resist composition used when the resist film is formed on the resistunderlayer film on which the intermediate layer is formed normally has asolid content of about 5% to 50% by mass, and is used after filteringthe resist composition through a filter having a pore size of about 0.2μm. A commercially available resist composition may be used in theprocess (2).

The coating method of the resist composition is not particularly limitedand the composition may be applied by spin coating or the like.

The prebaking temperature may be appropriately selected depending on thetype of the resist composition and the like, but is normally in therange from about 30° C. to 200° C., and preferably from 50° C. to 150°C.

In the process (3), the resist film is selectively exposed by applyingradiation to a given area of the resist film.

The radiation for exposure is appropriately selected from visible rays,ultraviolet rays, far-ultraviolet rays, X-rays, electron beams, γ-rays,molecular beams, ion beams, and the like depending on the type of aphotoacid generator contained in the resist composition. Among these,far-ultraviolet rays are preferable, and KrF excimer laser beams havinga wavelength of 248 nm, ArF excimer laser beams having a wavelength of193 nm, F₂ excimer laser beams having a wavelength of 157 nm, Kr₂excimer laser beams having a wavelength of 147 nm, ArKr excimer laserbeams having a wavelength of 134 nm, and extreme-ultraviolet rays havinga wavelength of 13 nm are particularly preferred.

The resist pattern-forming method of the embodiment of the presentinvention may not include a developing process (e.g., nanoimprintmethod).

In the process (4), the exposed resist film is developed using adeveloper to form a resist pattern.

The developer used in the process (4) is appropriately selectedaccording to the type of the resist composition. Specific examplethereof is an alkaline aqueous solution containing sodium hydroxide,potassium hydroxide, sodium carbonate, sodium silicate, sodiummetasilicate, ammonia, ethylamine, n-propylamine, diethylamine,di-n-propylamine, triethylamine, methyldiethylamine,dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide,tetraethylammonium hydroxide, pyrrole, piperidine, choline,1,8-diazabicyclo-[5.4.0]-7-undecene, or1,5-diazabicyclo-[4.3.0]-5-nonene.

The alkaline aqueous solution may contain an aqueous organic solventsuch as an alcohol including methanol and ethanol; a surfactant in anappropriate amount.

When the resist film after developing is subjected to rinsing anddrying, a given resist pattern can be formed.

In this process, the exposed resist film may be subjected topost-exposure bake (PEB) in order to improve the resolution, patternprofile, developability, and the like. The PEB temperature may beappropriately selected depending on the type of the resist compositionand the like. It is normally in the range from about 50° C. to 200° C.,and preferably from 70° C. to 150° C.

In the process (5), the intermediate layer and the resist underlayerfilm are dry-etched utilizing a gas plasma (e.g., oxygen plasma) usingthe resist pattern as a mask to form a given pattern for processing thesubstrate.

The pattern-forming method that utilizes the resist underlayerfilm-forming composition according to one embodiment of the embodimentof the invention may be a pattern-forming method that utilizes ananoimprint method or the like.

EXAMPLES

Hereinafter, the embodiments of the present invention are described indetail using Examples. The present invention is in no way limited bythese Examples. In addition, “part” and “%” in the description are basedon weight unless otherwise indicated.

1. Synthesis of Base Component (Resin Having Aromatic Ring) SynthesisExample 1

A separable flask equipped with a thermometer was charged with 100 partsof acenaphthylene, 78 parts of toluene, 52 parts of dioxane, and 3 partsof azobisisobutyronitrile in a nitrogen atmosphere. The mixture wasstirred at a temperature of 70° C. for 5 hours to obtain a resin havinga molecular weight of 10,000. After the addition of 5.2 parts ofp-toluenesulfonic acid monohydrate and 40 parts of paraformaldehyde, themixture was heated to 120° C., and stirred for 6 hours. The reactionsolution was poured into a large quantity of isopropanol, and aprecipitated resin was filtered to obtain a resin (A−1).

The weight average molecular weight (Mw) of the resin (A−1) was 20,000.

The weight average molecular weight (Mw) in Example was measured by gelpermeation chromatography (detector: differential refractometer) usingGPC columns manufactured by Tosoh Corporation (G2000HXL×2, G3000HXL×1)at a flow rate of 1.0 m1/min and a column temperature of 40° C. (eluant:tetrahydrofuran, standard: monodisperse polystyrene).

Synthesis Example 2

A reactor equipped with a condenser, a thermometer, and a stirrer wascharged with 100 parts of phenol, 100 parts of propylene glycolmonomethyl ether acetate, and 50 parts of paraformaldehyde. After theaddition of 2 parts of oxalic acid, the mixture was heated to 120° C.while dehydrating the mixture, and reacted for 5 hours to obtain a resin(A-2) having the following structural unit.

The weight average molecular weight (Mw) of the resin (A-2) was 7,000.

Synthesis Example 3

A reactor equipped with a condenser, a thermometer, and a stirrer wascharged with 100 parts of α-naphthol, 100 parts of propylene glycolmonomethyl ether acetate, and 50 parts of paraformaldehyde. After theaddition of 2 parts of oxalic acid, the mixture was heated to 120° C.while dehydrating the mixture, and reacted for 5 hours to obtain a resin(A-3) having the following structural unit.

The weight average molecular weight (Mw) of the resin (A-3) was 3,000.

Synthesis Example 4

A separable flask equipped with a thermometer was charged with 100 partsof styrene, 78 parts of toluene, and 3 parts of azobisisobutyronitrilein a nitrogen atmosphere. The mixture was stirred at a temperature of70° C. for 5 hours. The reaction solution was poured into a largequantity of isopropanol, and a precipitated resin was filtered to obtaina resin (A-4) having the following structural unit.

The weight average molecular weight (Mw) of the resin (A-4) was 10,000.

2. Preparation of Resist Underlayer Film-forming Composition 2-1.Examples 1 to 14 Example 1

10 parts of the resin (A−1) was dissolved in 1 part ofdihydroxybiphenyltetramethanol (compound (B−1) represented below) as acrosslinking agent, 0.1 part of diphenyliodoniumtrifluoromethanesulfonate (C−1) as a thermal acid generator and 90 partsof propylene glycol monomethyl acetate (D-1) as a solvent (see Table 1).The solution was filtered through a membrane filter having a pore sizeof 0.1 μm to prepare a resist underlayer film-forming composition forExample 1.

Examples 2 to 14

Resist underlayer film-forming compositions for Examples 2 to 14 wereprepared in the same manner as that in Example 1, except that the typeand the amount of each component were changed as shown in Table 1.

Note that the resins (A-2) to (A-4) used in Examples 2 to 4 (seeTable 1) were obtained in Synthesis Examples 2 to 4, respectively. Thecrosslinking agents (B−1) to (B-10) in Table 1 are shown below.

2-2. Comparative Examples 1 to 3 Comparative Example 1

10 parts of the resin (A−1) was dissolved in 1 part of1,3,4,6-tetrakis(methoxymethyl)glycoluril (compound (b-1) representedbelow) as a crosslinking agent, 0.1 part of diphenyliodoniumtrifluoromethanesulfonate (C−1) as a thermal acid generator and 90 partsof propylene glycol monomethyl acetate (D-1) as a solvent (see Table 1).The solution was filtered through a membrane filter having a pore sizeof 0.1 μm to prepare a resist underlayer film-forming composition forComparative Example 1.

Comparative Examples 2 and 3

Resist underlayer film-forming compositions for Comparative Examples 2and 3 were prepared in the same manner as that in Comparative Example 1,except that the type and the amount of each component were changed asshown in Table 1.

The crosslinking agents (b-1) to (b-3) in Table 1 are shown below.

TABLE 1 Base Crosslinking component agent Thermal acid (A) (B) generator(C) Solvent (D) (type/parts) (type/parts) (type/parts) (type/parts)Example 1 A-1/10 B-1/1 C-1/0.1 D-1/90 Example 2 A-2/10 B-1/1 C-1/0.1D-1/90 Example 3 A-3/10 B-1/1 C-1/0.1 D-1/90 Example 4 A-4/10 B-1/1C-1/0.1 D-1/90 Example 5 A-1/10 B-2/1 C-1/0.1 D-1/90 Example 6 A-1/10B-2/1 — D-1/90 Example 7 A-1/10 B-3/1 C-1/0.1 D-1/90 Example 8 A-1/10B-4/1 C-1/0.1 D-1/90 Example 9 A-1/10 B-5/1 C-1/0.1 D-1/90 Example 10A-1/10 B-6/1 C-1/0.1 D-1/90 Example 11 A-1/10 B-7/1 C-1/0.1 D-1/90Example 12 A-1/10 B-8/1 C-1/0.1 D-1/90 Example 13 A-1/10 B-9/1 C-1/0.1D-1/90 Example 14 A-1/10 B-10/1 C-1/0.1 D-1/90 Comparative A-1/10 b-1/1C-1/0.1 D-1/90 Example 1 Comparative A-1/10 b-2/1 C-1/0.1 D-1/90 Example2 Comparative A-1/10 b-3/1 C-1/0.1 D-1/90 Example 3

3. Evaluation of Resist Underlayer Film-forming Composition

The resist underlayer film-forming compositions obtained in Examples 1to 14 and Comparative Examples 1 to 3 were evaluated as described below.The results are shown in Table 2.

(1) Pattern Shape after Processing Substrate

Each resist underlayer film-forming composition obtained in Examples andComparative Examples was spin-coated onto an 8-inch silicon wafer,heated at a temperature of 180° C. for 60 seconds using a hot plate(oxygen concentration: 20 vol %), and then heated at 350° C. for 120seconds to form a resist underlayer film having a thickness of 0.3 μm.

After that, a three-layer resist process spin-on-glass compositionsolution (manufactured by JSR Corporation) was spin-coated onto theresist underlayer film, heated at a temperature of 200° C. for 60seconds, and then heated at 300° C. for 60 seconds using a hot plate toform an intermediate film having a thickness of 0.05 μm. Subsequently,an ArF resist composition solution (acrylic ArF photoresist manufacturedby JSR Corporation) was spin-coated onto the intermediate film, andprebaked at a temperature of 130° C. for 90 seconds using a hot plate toform a resist film having a thickness of 0.2 μm. The resist film wasthen exposed via a mask pattern for an optimum exposure time using anArF excimer laser exposure system manufactured by Nikon Corporation(numerical aperture: 0.78, exposure wavelength: 193 nm). Afterpostbaking the resist film at a temperature of 130° C. for 90 secondsusing a hot plate, the resist film was developed at a temperature of 25°C. for 1 minute using a 2.38% tetramethylammonium hydroxide aqueoussolution, rinsed with water, and dried to obtain an ArF positive-toneresist pattern. The intermediate film was processed using the resistpattern as a mask, and the resist underlayer film was processed usingthe intermediate film as a mask. The substrate was processed using theresist underlayer film as a mask.

The shape of the resulting pattern was observed using a scanningelectron microscope, and evaluated in accordance with the followingcriteria.

-   “Acceptable”: The pattern of the resist underlayer film stood    upright.-   “Unacceptable”: The pattern of the resist underlayer film collapsed    or bent.    (2) Etching Resistance

Each resist underlayer film-forming composition obtained in Examples andComparative Examples was spin-coated onto an 8-inch silicon wafer,heated at a temperature of 180° C. for 60 seconds using a hot plate(oxygen concentration: 20 vol %), and then heated at 350° C. for 120seconds to form a resist underlayer film having a thickness of 0.3 μm.The resist underlayer film was etched using an etching system “EXAM”manufactured by Shinko Seiki Co., Ltd. The conditions were CF₄/Ar/O₂(CF₄: 40 ml/min, Ar: 20 ml/min, O₂: 5 ml/min), pressure: 20 Pa, RFpower: 200 W, etching time: 40 sec, and temperature: 15° C.

The etching rate was calculated based on the thickness of the resistunderlayer film measured before and after etching, and the etchingresistance was evaluated in accordance with the following criteria.

-   “Acceptable”: The etching rate was 150 nm/min or less.-   “Fair”: The etching rate was more than 150 and less than 200 nm/min.-   “Unacceptable”: The etching rate was 200 nm/min or more.    (3) Elemental Composition

Each resist underlayer film-forming composition obtained in Examples andComparative Examples was spin-coated onto an 8-inch silicon wafer,heated at a temperature of 180° C. for 60 seconds using a hot plate(oxygen concentration: 20 vol %), and then heated at 350° C. for 120seconds to form a resist underlayer film having a thickness of 0.3 μm.The weight percent of each element contained in the resist underlayerfilm was calculated using a carbon-hydrogen-nitrogen analyzer “JM10”manufactured by J-Science Lab Co., Ltd.

The number of respective atoms contained in the resist underlayer filmwas calculated by “weight percent (wt %) of elements/mass (g) ofelements”, and the hydrogen content (atom %) after dehydrogenation wascalculated by “number of hydrogen atoms contained in resist underlayerfilm/total number of atoms contained in resist underlayer film”.

The hydrogen content before dehydrogenation was measured using a resistunderlayer film formed by spin-coating the resist underlayerfilm-forming composition onto an 8-inch silicon wafer, and heating theapplied composition at a temperature of 200° C. for 60 seconds using ahot plate (oxygen concentration: 20 vol %).

TABLE 2 Hydrogen content (atom %) Before After Etching dehy- dehy-Pattern shape resistance drogenation drogenation Example 1 AcceptableAcceptable 50 35 Example 2 Acceptable Fair 50 30 Example 3 AcceptableAcceptable 40 25 Example 4 Acceptable Fair 40 25 Example 5 AcceptableAcceptable 50 35 Example 6 Acceptable Fair 50 30 Example 7 AcceptableAcceptable 40 25 Example 8 Acceptable Acceptable 40 25 Example 9Acceptable Fair 40 25 Example 10 Acceptable Acceptable 50 35 Example 11Acceptable Acceptable 50 30 Example 12 Acceptable Fair 40 25 Example 13Acceptable Acceptable 50 35 Example 14 Acceptable Acceptable 50 30Comparative Unacceptable Acceptable 50 47 Example 1 ComparativeUnacceptable Fair 50 48 Example 2 Comparative Unacceptable Fair 50 47Example 3

As is clear from Table 2, resist underlayer films excellent in patterntransfer capability and etching resistance could be formed using theresist underlayer film-forming compositions obtained in Examples 1 to14.

According to the resist underlayer film-forming composition of theembodiment of the present invention, a resist underlayer film can beformed which leads to excellent etching resistance, and suppresses asituation in which the underlayer film pattern is bent when transferringa fine pattern by etching. Therefore, the resist underlayer film-formingcomposition is more suitably used for microfabrication employed in alithographic process. Particularly the resulting resist underlayer filmexhibits an excellent pattern transfer capability and excellent etchingselectivity during a dry etching process, in other words, the resistunderlayer film is rarely over-etched, and the resist pattern can betransferred to the substrate with good reproducibility. In addition,since the underlayer film pattern is not bent when etching thesubstrate, an increase in yield is expected to be achieved inmicrofabrication employed in a lithographic process, and particularlythe production of integrated circuit devices.

The pattern-forming method of the embodiment of the present inventionutilizing such a resist underlayer film-forming composition may beuseful for a lithographic process, and particularly an integratedcircuit device production process. More specifically, the embodiment ofthe present invention relates to a pattern-forming method that utilizesoxidative crosslinking due to dehydrogenation when forming a resistunderlayer film, and may suitably be used for microfabrication employedin a lithographic process that utilizes various types of radiation(particularly production of integrated circuit devices), and a resistunderlayer film-forming composition used for the pattern-forming method.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

The invention claimed is:
 1. A pattern-forming method comprising:applying a resist underlayer film-forming composition on a substrate;heating the resist underlayer film-forming composition at a temperatureof no less than 200° C. to form a resist underlayer film; forming anintermediate layer on the resist underlayer film; applying a resistcomposition to the resist underlayer film on which the intermediatelayer is formed to form a resist film; exposing the resist film byselectively applying radiation to the resist film; developing theexposed resist film to form a resist pattern; and dry-etching theintermediate layer, the resist underlayer film, and the substrate usingthe resist pattern as a mask to form a given pattern on the substrate,the resist underlayer film-forming composition comprising: a basecomponent which is a novolac resin, a resol resin, a styrene resin, anacenaphthylene resin, or a resin having a fullerene skeleton; and acrosslinking agent having a partial structure represented by formula(i),

wherein X represents an oxygen atom, a sulfur atom, or —NR—, wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, and in a case where aplurality of X are present, each of the plurality of X is eitheridentical or different, n₁ is an integer from 1 to 6, and R¹ representsa hydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 30 carbon atoms, wherein in a case where a pluralityof R¹ are present, each of the plurality of R¹ is either identical ordifferent, wherein the resist underlayer film comprises hydrogen atoms,and a content of the hydrogen atoms in the resist underlayer film isdecreased to no greater than 35 atom % by the heating to form the resistunderlayer film.
 2. The pattern-forming method according to claim 1,wherein the crosslinking agent is a compound represented by formula(b1-1), a compound represented by formula (b2), or both thereof,

wherein X represents an oxygen atom, a sulfur atom, or —NR—, wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, and in a case where aplurality of X are present, each of the plurality of X is identical ordifferent, n₂ is an integer from 1 to 5, n₃ is independently an integerfrom 1 to 4, m is independently 0 or 1, R¹ represents a hydrogen atom,an alkyl group having 1 to 9 carbon atoms, or an aryl group having 6 to30 carbon atoms, wherein in a case where a plurality of R¹ are present,each of the plurality of R¹ is identical or different, R² represents ahydrogen atom, a hydroxyl group, an alkyl group having 1 to 9 carbonatoms, or an aryl group having 6 to 22 carbon atoms, wherein in a casewhere a plurality of R² are present, each of the plurality of R² iseither identical or different, and R³ represents a single bond, anoxygen atom, an ester group, a carbonyl group, a chain hydrocarbon grouphaving 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbonatoms, a nitrogen atom, a sulfur atom, or an (n₂+1)-valent group whichis an arbitrary combination thereof,

wherein X represents an oxygen atom, a sulfur atom, or —NR—, wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, and in a case where aplurality of X are present, each of the plurality of X is eitheridentical or different, n₄ is an integer from 1 to 5, m is 0 or 1, R¹represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms, wherein in a case where aplurality of R¹ are present, each of the plurality of R¹ is eitheridentical or different, and R² represents a hydrogen atom, a hydroxylgroup, an alkyl group having 1 to 9 carbon atoms, or an aryl grouphaving 6 to 22 carbon atoms.
 3. The pattern-forming method according toclaim 1, wherein the crosslinking agent is a compound represented byformula (b1-2),

wherein n₅ is an integer from 1 to 5, R⁵ represents independently ahydrogen atom, an alkyl group having 1 to 9 carbon atoms, or an arylgroup having 6 to 30 carbon atoms, and R⁶ represents a single bond, anoxygen atom, an ester group, a carbonyl group, a chain hydrocarbon grouphaving 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbonatoms, a nitrogen atom, a sulfur atom, or an (n₅+1)-valent group whichis an arbitrary combination thereof.
 4. The pattern-forming methodaccording to claim 1, wherein the crosslinking agent is a compoundrepresented by formula (b1-3),

wherein R⁸ represents independently a hydrogen atom, an alkyl grouphaving 1 to 9 carbon atoms, or an aryl group having 6 to 30 carbonatoms, and R⁹ represents a single bond, an oxygen atom, an ester group,a carbonyl group, a chain hydrocarbon group having 1 to 30 carbon atoms,an alicyclic hydrocarbon group having 3 to 30 carbon atoms, an aromatichydrocarbon group having 6 to 30 carbon atoms, a sulfur atom, —NR—, or adivalent group which is an arbitrary combination thereof, wherein Rrepresents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms,or an aryl group having 6 to 30 carbon atoms.
 5. The pattern-formingmethod according to claim 1, wherein the resist underlayer film-formingcomposition further comprises a solvent.
 6. The pattern-forming methodaccording to claim 1, wherein a content of hydrogen atoms in the resistunderlayer film is no less than 25 atom % and no greater than 35% afterthe heating to form the resist underlayer film.